<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <input type="button" value="获取笑话" @click="getJoke">
        <p>{{joke}}</p>
    </div>
    <script src="https://unpkg.com/axios/dist/axios.min.js"></script>

    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

    <script>
        var app = new Vue({
            el: "#app",
            data: {
                joke: "笑话"
            },
            methods: {
                getJoke() {
                    var that = this
                    axios.get("https://autumnfish.cn/api/joke").then(function (rep) {
                        console.log(rep)
                        // 这里的this指向已经变化
                        that.joke = rep.data
                    }, function (err) {
                        console.log(err)
                    })
                }
            }
        })
    </script>

</body>

</html>